Turbomachine with trapped vortex feature

ABSTRACT

A turbomachine with a trapped vortex feature includes a unibody liner formed to define a flow path for combustion products, the unibody liner including first and second portions defining first radial planes, a third portion defining a second radial plane and fourth and fifth portions extending substantially radially between proximal ends of the first and third portions and proximal ends of the second and third portions, respectively, and an injector configured to deliver a fuel or a fuel/air mixture to a space partially bound by the third, fourth and fifth portions.

BACKGROUND OF THE INVENTION

The subject matter disclosed herein relates to turbomachines and, moreparticularly, to turbomachines with trapped vortex features.

A typical turbomachine includes a compressor to compress inlet air, acombustor in which the compressed inlet air is combusted along withfuel, a turbine in which products of the combustion are receivable forpower generation purposes and a transition piece. The transition pieceis fluidly interposed between the combustor and the turbine.

In some cases, the typical turbomachine is configured to support axiallystaged or late lean injection. In these cases, fuel and air are injectedinto downstream sections of the combustor or the transition piece inorder to cause secondary combustion within the downstream sections ofthe combustor or the transition piece. This secondary combustion tendsto reduce emissions of pollutants, such as oxides of nitrogen.

BRIEF DESCRIPTION OF THE INVENTION

According to one aspect of the invention, a unibody liner formed todefine a flow path for combustion products, the unibody liner includingfirst and second portions defining first radial planes, a third portiondefining a second radial plane and fourth and fifth portions extendingsubstantially radially between proximal ends of the first and thirdportions and proximal ends of the second and third portions,respectively, and an injector configured to deliver a fuel or a fuel/airmixture to a space partially bound by the third, fourth and fifthportions.

According to another aspect of the invention, a turbomachine is providedand includes a unibody liner formed to define a flow path for combustionproducts, the unibody liner being formed to define a trapped vortexfeature into which a portion of combustion products flow, and aninjector configured to deliver a fuel or a fuel/air mixture to thetrapped vortex feature.

According to yet another aspect of the invention, a turbomachine isprovided and includes a combustor liner defining a first interior inwhich combustion occurs and a second interior through which products ofcombustion flow, a transition piece disposed downstream from thecombustor liner, the transition piece defining a third interior, whichis receptive of the products of combustion and through which theproducts of combustion continue to flow, at least one of the combustorliner and the transition piece being formed to define a recess intowhich a portion of the products of combustion flow and an injectorconfigured to deliver combustible materials to the recess whereby thecombustible materials and the portion of the products of combustion formrespectively trapped vortices.

These and other advantages and features will become more apparent fromthe following description taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter, which is regarded as the invention, is particularlypointed out and distinctly claimed in the claims at the conclusion ofthe specification. The foregoing and other features, and advantages ofthe invention are apparent from the following detailed description takenin conjunction with the accompanying drawings in which:

FIG. 1 is a schematic illustration of a turbomachine; and

FIG. 2 is an enlarged view of a portion of the turbomachine of FIG. 1.

The detailed description explains embodiments of the invention, togetherwith advantages and features, by way of example with reference to thedrawings.

DETAILED DESCRIPTION OF THE INVENTION

With reference to FIGS. 1 and 2, a turbomachine 10 includes a compressor11 to compress inlet air, a combustor 12 in which the compressed inletair is combusted along with fuel, a turbine 13 in which products ofcombustion are receivable for power generation purposes and a transitionpiece 14. The transition piece 14 is fluidly interposed between thecombustor 12 and the turbine 13. The turbomachine 10 is configured tosupport axially staged injection or late lean injection (LLI) wherebyfuel and air are injected into downstream sections of the combustor 12or the transition piece 14 in order to cause secondary combustionprocesses. This secondary combustion tends to reduce emissions ofpollutants, such as oxides of nitrogen, from the turbomachine 10.

In some axially staged injection or LLI configurations, it has beenfound that almost all of the air available for turbomachine operationsis utilized for combustion in one form or another and that little to noair is bypassed in the form of combustor dilution air. This means thatair used for axially staged injection or LLI robs the head end of thecombustor 12 of some portion of air that could have otherwise been usedto improve head end performance for a given amount of fuel. Accordingly,the turbomachine 10 is provided with a trapped vortex feature (which isdescribed below) that allows most of the air available for combustion tobe provided through the pre-mixers at the head end of the combustor 12and then be re-utilized later for axially staged injection or LLI.

With reference to FIG. 2, the combustor 12 includes a combustor liner 20and a flow sleeve 21. The combustor liner 20 is formed to define a firstinterior 201, in which a first stage of the combustion occurs, and asecond interior 202. The products of combustion flow through the secondinterior 202 toward the turbine 13. The first interior 201 is generallydefined proximate to a head end of the combustor 12 at an axiallyupstream location and the second interior 202 is defined fluidly andaxially downstream from the first interior 201. The flow sleeve 21 isdisposed about the combustor liner 20 to define a first annulus 22.

The transition piece 14 is disposed fluidly and axially downstream fromthe combustor 12 and includes a transition piece liner 30 and animpingement sleeve 31. The transition piece liner 30 is formed to definea third interior 301, which is fluidly interposed between the secondinterior 202 and an interior of the turbine 13. Thus, the third interior301 is receptive of the products of combustion from the second interior202 of the combustor 12 and provides for a flow path along or throughwhich the products of combustion can continue to flow toward the turbine13. The impingement sleeve 31 is disposed about the transition pieceliner 30 to define a second annulus 32. The second annulus 32 is fluidlycoupled with the first annulus 22. The impingement sleeve 31 is formedto define impingement holes 310.

For purposes of clarity and brevity, in the following description andclaims, the combustor liner 20 and the transition piece liner 30 may bereferred to separately or as a unibody liner. Thus, it will beunderstood that a unibody liner includes at least portions of both thecombustor liner 20 and the transition piece liner 30.

Compressed air is exhausted from the compressor 11 and enters acompressor discharge casing (CDC). From an interior of the CDC, thecompressed air enters the second annulus 32 via the impingement holes310. The compressed air then flows from the second annulus 32 throughthe first annulus 22 toward the head end of the combustor 12 where thecompressed air is mixed with fuel and combusted.

In some cases, a portion of the compressed air entering the secondannulus 32 may be used as a coolant for the transition piece liner 30within the third interior 301. In such cases, the transition piece liner30 may include a flange 33 that is sealed to the transition piece liner30 by hula seal 34. The flange 33 is formed to define a cooling path 35by which the portion of the compressed air can be delivered to the thirdinterior 301 along an interior surface of the transition piece liner 30.

At least one or both of the combustor liner 20 and the transition pieceliner 30 is formed to define a substantially annular recess 40 proximateto a connection of the combustor liner 20 and the transition piece liner30. The recess 40 acts as a trapped vortex feature 41 that extendsradially outwardly from the second interior 202 and/or the thirdinterior 301. Thus, as the products of combustion travel downstreamthrough the second interior 202 and then through the third interior 301as a main flow, a portion of the products of combustion flow into therecess 40 with a flow pattern (i.e., a second trapped vortex 70) to bedescribed below. In accordance with embodiments, the portion of theproducts of combustion include air provided through the pre-mixers atthe head end of the combustor 12 and which is to be re-utilized in therecess 40/trapped vortex feature 41.

In being formed to define the recess 40, the at least one of thecombustor liner 20 and the transition piece liner 30 includes a firstaxial portion 401, a second axial portion 402, a third axial portion403, a fourth radial portion 404 and a fifth radial portion 405 with therecess at least partially bounded by the third axial portion 403, thefourth radial portion 404 and the fifth radial portion 405. The firstaxial portion 401 may be disposed upstream from the second axial portion402. The first and second axial portions 401 and 402 may have annularshapes while respectively defining first radial planes, RP1, which maybe but need not be substantially similar to one another. The third axialportion 403 may have an annular shape and defines a second radial plane,RP2, which is displaced radially outwardly from the first radial planes,RP1, by a predefined amount. The fourth radial portion 404 and the fifthradial portion 405 each extend substantially radially to connect thefirst and second axial portions 401 and 402 to the third axial portion403. That is, the fourth radial portion 404 extends substantiallyradially between proximal ends of the first axial portion 401 and thethird axial portion 403 while the fifth radial portion 405 extendssubstantially radially between proximal ends of the second axial portion402 and the third axial portion 403.

In accordance with embodiments, the recess 40 may have a substantiallyrectangular cross-sectional shape. In accordance with furtherembodiments, the corners of the recess 40 (i.e., the connections betweenthe first axial portion 401 and the fourth radial portion 404, thefourth radial portion 404 and the third axial portion 403, the thirdaxial portion 403 and the fifth radial portion 405 and the fifth radialportion 405 and the second axial portion 402) may be rounded tofacilitate smooth fluid flow into and out of the recess 40.

The turbomachine 10 further includes an injector 50. The injector 50 isconfigured to deliver combustible materials, such as a fuel or a fueland air mixture, to the recess 40. In so doing, the combustiblematerials form a first trapped vortex 60 while the portion of theproducts of combustion that have flown into the recess 40 form thesecond trapped vortex 70. The combustible materials may include, forexample, fuel and a quantity of air derived from the CDC. As such, thecombustible materials have a pressure, P_(CD), which is substantiallysimilar to the pressure in the CDC interior.

As shown, the combustible materials forming the first trapped vortex 60tend flow in a first vortical pattern and the portion of the products ofcombustion forming the second trapped vortex 70 tends to flow in asecond vortical pattern. The first and second vortical patterns may besubstantially oppositely oriented. Thus, as the first and secondvortices 60 and 70 are adjacent to one another, the respective fluids ineach one mix along the shear line 80 such that the combustible materialsinjected into the recess 40 by the injector 50 auto-ignite due to thetemperatures and pressures of the portion of the products of combustion.The respective fluids, including the auto-ignited combustible materials,are then returned to the main flow and proceed to flow toward theturbine 13.

With the auto-ignited combustible materials returned to the main flow,axially staged injection or LLI processes may be engaged. This allowsfor secondary combustion to occur with the associated advantages interms of reduced pollutant emissions, for example, but without the needto deprive the head end of the combustor 12 of any of the air necessaryfor a given amount of fuel.

The injector 50 may include a vane 51 and a fuel source 52. The vane 51is formed to define a flowpath 510 by which the compressed air istransmittable from the CDC to the recess 40. The fuel source 52 mayinclude a flexible hose 520 and is configured to provide a supply offuel to the flowpath 510. The vane 51 is substantially radially orientedand traverses the first annulus 22 and/or the second annulus 32. Thevane 51 may be cylindrical or otherwise aerodynamically formed togenerate as little a disturbance as possible in compressed air movingthrough the first annulus 22 or the second annulus 32. The vane 51 mayinclude a micromixer 511 that is formed to mix the combustible materialsto be injected into the recess 40 and to prevent or substantially reducethe possibility of flameholding in the recess 40 or the vane 51.

For most of the radial length of the vane 51, the flowpath 510 isoriented substantially radially. At a radially inward location, however,the vane 51 may be configured such that the flowpath 510 runs along theaxial dimension of the turbomachine 10. In this way, the injector 50 isconfigured to inject the combustible materials into the recess 40 in asubstantially axial direction thus facilitating the formation of thefirst trapped vortex 60.

In accordance with further embodiments, the fifth radial portion 405 maybe formed to define through-hole 53 by which compressed air may flowfrom the second annulus 32 into the recess 40. In this way, additionalair may be provided to enhance the combustion of the fuel injected bythe injector 50. Moreover, since the through-hole 53 is defined throughthe fifth radial portion 405, the through-hole has a substantially axialorientation whereby the compressed air flowing through the through-hole53 flows in the axial direction and thereby facilitates the formation ofthe first trapped vortex 60. It will be understood that a similar effectcan be achieved with the through-hole 53 defined through a downstreamsection of the third axial portion 403. In this case, the compressed airflowing into the recess flows in the radial direction and againfacilitates the formation of the first trapped vortex 60.

While the invention has been described in detail in connection with onlya limited number of embodiments, it should be readily understood thatthe invention is not limited to such disclosed embodiments. Rather, theinvention can be modified to incorporate any number of variations,alterations, substitutions or equivalent arrangements not heretoforedescribed, but which are commensurate with the spirit and scope of theinvention. Additionally, while various embodiments of the invention havebeen described, it is to be understood that aspects of the invention mayinclude only some of the described embodiments. Accordingly, theinvention is not to be seen as limited by the foregoing description, butis only limited by the scope of the appended claims.

1. A turbomachine with a trapped vortex feature, comprising: a unibodyliner formed to define a flow path for combustion products, the unibodyliner comprising: first and second portions defining first radialplanes, a third portion defining a second radial plane and fourth andfifth portions extending substantially radially between proximal ends ofthe first and third portions and proximal ends of the second and thirdportions, respectively; and an injector configured to deliver a fuel ora fuel/air mixture to a space partially bound by the third, fourth andfifth portions.
 2. The turbomachine according to claim 1, wherein theinjector is configured to deliver the fuel or the fuel/air mixture tothe space in a substantially axial direction.
 3. The turbomachineaccording to claim 1, wherein the unibody liner comprises a combustorliner and a transition piece liner and the space is defined proximate toa connection of the combustor liner and the transition piece.
 4. Theturbomachine according to claim 1, wherein the space has an annularshape.
 5. The turbomachine according to claim 1, wherein the space has asubstantially rectangular cross-sectional shape.
 6. A turbomachine,comprising: a unibody liner formed to define a flow path for combustionproducts; the unibody liner being formed to define a trapped vortexfeature into which a portion of combustion products flow; and aninjector configured to deliver a fuel or a fuel/air mixture to thetrapped vortex feature.
 7. The turbomachine according to claim 6,wherein the injector is configured to deliver the fuel or the fuel/airmixture to the trapped vortex feature in a substantially axialdirection.
 8. The turbomachine according to claim 6, wherein the unibodyliner comprises a combustor liner and a transition piece liner and thetrapped vortex feature is defined proximate to a connection of thecombustor liner and the transition piece.
 9. The turbomachine accordingto claim 6, wherein the trapped vortex feature has an annular shape. 10.The turbomachine according to claim 6, wherein the trapped vortexfeature has a substantially rectangular cross-sectional shape.
 11. Aturbomachine, comprising: a combustor liner defining a first interior inwhich combustion occurs and a second interior through which products ofcombustion flow; a transition piece liner disposed downstream from thecombustor liner, the transition piece liner defining a third interior,which is receptive of the products of combustion and through which theproducts of combustion continue to flow, at least one of the combustorliner and the transition piece liner being formed to define a recessinto which a portion of the products of combustion flow; and an injectorconfigured to deliver combustible materials to the recess whereby thecombustible materials and the portion of the products of combustion formrespectively trapped vortices.
 12. The turbomachine according to claim11, wherein the combustible materials comprise fuel or a fuel mixed withcompressor discharge casing air.
 13. The turbomachine according to claim11, further comprising: a flow sleeve disposed about the combustor linerto define a first annulus; and an impingement sleeve disposed about thetransition piece liner to define a second annulus, the second annulusbeing fluidly coupled to the first annulus.
 14. The turbomachineaccording to claim 11, wherein the injector comprises: a vane formed todefine a flowpath by which air is transmitted from a compressordischarge casing to the recess; and a fuel source configured to providea supply of fuel to the flowpath.
 15. The turbomachine according toclaim 14, wherein the vane comprises a micromixer.
 16. The turbomachineaccording to claim 14, wherein the fuel source comprises a flexiblehose.
 17. The turbomachine according to claim 11, wherein the injectoris configured to deliver the combustible materials to the recess in asubstantially axial direction.
 18. The turbomachine according to claim11, wherein the recess is defined proximate to a connection of thecombustor liner and the transition piece liner.
 19. The turbomachineaccording to claim 11, wherein the recess has an annular shape.
 20. Theturbomachine according to claim 11, wherein the recess has asubstantially rectangular cross-sectional shape.